JPH0285909A - Digital function generator - Google Patents

Abstract

PURPOSE:To minimize the memory capacity by outputting the values of a prescribed function and a function in accordance with a switch command based on the function value that stores the prescribed function or the function which prescribes uniquely the corresponding relation between a parameter complement and the value equal to the prescribed function. CONSTITUTION:A memory means 2 outputs the function value corresponding to the parameter received from the outside. A switch means 3 outputs an input logic variable or the complement of the logic variable to the means 2 as a parameter by an external switching command. Then the parameter obtained by performing the switch between the input logic variable and its complement based on a switching command is applied. The values of a prescribed function and a function are outputted by a switching command and based on the function value of the prescribed function or the function which prescribes uniquely the corresponding relation between the parameter complement and the value equal to the prescribed function value. As a result, the memory capacity is minimized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a digital function generator that is effective in reducing storage capacity.

[Prior Art] It has been known to share various functional parts in order to reduce the mounting area of various elements such as integrated circuits constituting a digital circuit. For example, the following techniques have been proposed as such techniques. (1) An "address selection circuit" that serially inputs address information via a single signal line to an address selection circuit consisting of a shift circuit and a comparator, thereby reducing the area ratio of the address information in the entire integrated circuit. ” (Unexamined Japanese Patent Publication No. 61-662
Publication No. 83).

(2) A "semiconductor memory device" that uses a shift register to select word lines and suppress the area of the word line selection section (
JP-A-62-22291).

[Problems to be Solved by the Invention] However, the conventional technology reduces the mounting area of signal transmission paths such as address buses and word line selection sections, and for example, reduces the mounting area of the original functional parts of elements such as memory sections. There was a problem in that no consideration was given to reducing the mounting area by reducing the storage capacity.

This is true, for example, in a function generator that stores function values for various numbers and outputs function values in response to external input signals, as the number of stored functions increases. This brings about the problem of increased capacity, and the conventional technology is still not sufficient.

SUMMARY OF THE INVENTION An object of the present invention is to provide a digital function generator capable of outputting two types of function values having a specific relationship with a minimum storage capacity.

[Means for Solving the Problems] The present invention, which has been made to achieve the above object, provides a predetermined function that uniquely defines the correspondence between parameters and function values;
Stores only the function value of one of the functions that uniquely defines the correspondence between the complement of the above parameter and the same function value as the above function value, and outputs the function value corresponding to the parameter transmitted from the outside. It is characterized by comprising: a memory/storage means; and a switching means for outputting either an input logic variable or a complement of the logic variable as a parameter to the storage means in accordance with an external switching command. This paper focuses on digital function generators.

[Operation] In the digital function generator of the present invention, the switching means outputs either the input logic variable or the complement of the logic variable as a parameter to the storage means in accordance with an external switching command. Then, the function value of either a predetermined function that uniquely defines the correspondence between a parameter and a function value, or a function that uniquely defines a correspondence between the complement of the parameter and the function value that is the same as the function value. The storage means for storing only the parameters is operative to output a function value corresponding to the parameter transmitted from the switching means.

In other words, a parameter obtained by switching the input logical variable and its complement according to a switching command is given, and the correspondence between a predetermined function or the complement of the parameter and a function value that is the same as the function value of the predetermined function is uniquely determined. From the stored function values of only one of the functions defined by the function, the predetermined function and the double aperture value of the above function are output in response to a switching command.

Thus, the digital function generator of the present invention serves to generate, with a minimum of storage capacity, the double value of a predetermined function and a function having a specific relationship to the predetermined function.

[Embodiment] Next, a preferred embodiment of the present invention will be described in detail based on the drawings. FIG. 1 shows a schematic configuration of a trigonometric function generator that is an embodiment of the present invention.

As shown in the figure, the trigonometric function generator 1 is composed of a semiconductor memory 2 and a gate circuit 3.

The semiconductor memory 2 has an address terminal 1 to which input data of 4 [bitl] corresponding to the angle θ is input from the gate circuit 3.
1.12, 13.14 (address terminal 11 is the lowest),
An output terminal 15 that outputs output data that is a function value of a sine function corresponding to input data (angle θ). 1
6. 17. 18 (output terminal 15 is the lowest).

The cable circuit 3 has an input terminal 21. to which an angle signal corresponding to the angle θ is input. 22. 23. 24. Control terminal for inputting a switching signal for outputting either a sine function value or a cosine function value for the angle θ 25. Four 2-input 1-output exclusive OR circuits (hereinafter referred to as EX-OR') 31, 32
, 33.34. Each EX-OR31,
One input terminal of 32, 33, 34 is the input terminal 21. 2
2. 23°24, and the other input terminal is all control terminal 25
Each output side is connected to an address terminal 11. 12. 13
．． 14, respectively. When the switching signal at the control terminal 25 is at a low level 011, the gate circuit 3 uses the angle signals input to the input terminals 21, 22, 23, and 24 as input data as they are;
When the switching signal is high and level ``1'', the complement of the angle signal input to the input terminals 21, 22, 23, and 24 is used as input data, and the address terminals 11... of the semiconductor memory 2 are respectively input. 12. 13. Output to 14.

As shown in FIG. 2, the semiconductor memory 2 has address terminals 11, 12, 13.14 and output terminals 15, 16, 17, .
18, a plurality of NOT circuits 41.5 input 1 output AND circuit 42, MO9 type field effect transistor 43.
44 is interposed therebetween. As shown in FIG. 3, this semiconductor memory 2 stores the function value of the sine function 5IN(θ) at angular intervals (6°×90°) up to an angle (0° to 90°).
715). That is, 2 bits of 4 bits are applied to address terminals 11, 12, 13, and 14 shown in FIG.
When base input data nb (value equivalent to decimal number n) is input, it is stored at the address corresponding to this input data nb, and the sine function value 4[b i t
] is output as a binary approximate value Nb (decimal N).

N = 15XSIN (90°/15Xn
)... (1) However, 0≦n≦15 Next, the operation of the trigonometric function generator 1 will be explained. First, the switching signal input to the control terminal 25 is at low level 11011.
In the case of input terminal 21. 22. The angle signal nbl (corresponding to decimal number nl) input to 23°24 is directly passed through the gate circuit 3 to address terminals 11, 12, 1.
3.14 is input as binary input data nbl. Therefore, the output terminals 15, 16, 17, and 18 output a sine function value N1 (in decimal notation) expressed by the following equation (2).

Nl = 15XSIN (90° /15
On the other hand, when the switching signal input to the control terminal 25 is at a high level "+1", the input terminals 21. 22. 23.2
The binary angle signal n1 input to 4 is the angle signal n1
is converted into one's complement nlc (nl c= (15-nl)), and then sent to address terminals 11, 1 via gate circuit 3.
2.13.14 is input as binary input data nlc. Therefore, from the output terminals 15.16 and 17.18, a sine function value NIC (decimal number) shown by the following equation (3) is output.

NIC= 15XSIN (90°/15Xnlc) = 15 X SIN (90'/15X
(15-n 1) ) ... (3) However,
Equation (3) expresses the angle signal nl as shown in the following equation (4).
(in decimal notation) is equal to the cosine function value NIC9 (in decimal notation).

NIC9= 15 x CO9 (90°/15 x nl)...(
4) Therefore, when the switching signal input to the control terminal 25 is pi level +1111, the output terminal 15.16°17.1
8, the cosine function value NIC8 of the angle signal n1 is output as a binary number. That is, as shown in FIG. 3, when the angle signal n=5 (decimal number) is input and the switching signal is low level "0", the address terminals 11, 12, 13.1
0101” (binary number) is input to 4. Then,
As shown in the figure, from output terminals 15.16 and 17.18, "1000" (binary number), function @ value N1 = 7
゜5≠8 (decimal number) is output. This function value is an approximation of the sine function value. On the other hand, the switching signal is at a high level.
In the case of +1'', ``1010'' (binary number) is input to address terminals 11, 12, 13, and 14. Then, as shown in the same figure, output terminals 15.16, 17.1
From 8, the cosine function value "1101" (binary number), NIC
5=12.9ζ13 (decimal number) is output. This cosine function value is an approximate value of a 2 [bit] cosine function value.

In this way, when the switching signal is at the low level "0", a sine function value is output, and when the switching signal is at the high level, a cosine function value is output.

In this embodiment, the semiconductor memory 2 corresponds to storage/memory means, and the gate circuit 3 corresponds to switching means.

As described above, according to this embodiment, it is possible to generate double open values of the sine function (SIN) and the cosine function (CO8) while keeping the memory area to a minimum.

In addition, the semiconductor memory 2 and the exclusive OR circuit (EX-O
R) It can be realized by a simple circuit configuration in combination with the gate circuit 3 consisting of 31.32 and 33.34.

In this way, the memory capacity and mounting area of the trigonometric function generator 1 can be reduced.

Further, when a cosine function value is stored in the semiconductor memory 2, a cosine function (direct) can be output when the switching signal is at a low level +l□I+, and a sine function vi value can be output when the switching signal is at a high level ++111.

In this embodiment, the case of a sine function and a cosine function has been explained. However, for example, the trigonometric function TAN (θ
) and COT (θ) have a relationship as shown in the following equation (5).

TAN (7T/2-θ)=COT(θ)... (5
) Therefore, the value of either TAN (θ) or C0T (θ) is stored in a semiconductor memory, the input signal is transmitted through the gate circuit, and the input data and its complement are switched by the control terminal input signal. When configured, TAN (, θ
) and COT (θ) (direct) are obtained.

In addition, in general, two functions f that satisfy the relationship of the following equation (6)
(x), g (X) can also be applied.

f (T-x) = g (x) ... (
6) - As an example, the same effect can be obtained even if the analogy is applied to both the functions of the following equations (7) and (8).

y:=x2...(7
)y = (2”-1-x) ... (
8) Furthermore, in this embodiment, the input signal is 4 [b i
t]. However, for example, even if the number of digits of the input signal is arbitrarily increased or decreased, the same effect as in the above embodiment can be obtained.

[Effects of the Invention] As detailed above, the digital function generator of the present invention provides a parameter obtained by switching the input logic variable and its complement according to a switching command, and generates a predetermined function or a parameter of the above parameter. Switching the double open value of the predetermined function and the above function from the stored function value of only one of the functions that uniquely defines the correspondence between the complement and the same function value as the function value of the above predetermined function. It is configured to output according to commands. Therefore, it is possible to provide the double arithmetic value of a predetermined function and a function having a specific relationship with the predetermined function with a minimum storage capacity, which is an excellent effect.

Furthermore, with the above effects, the storage capacity and mounting space of the digital function generator can be reduced.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of an embodiment of the present invention, FIG. 2 is a circuit diagram thereof, and FIG. 3 is an explanatory diagram showing the relationship between input data and output data. 1...Trigonometric function generator, 2...Semiconductor memory, 3.
...Gate circuit, 15.16, 17.18...Output terminal, 21.22.23.24...Input terminal, 25--
・Control terminal figure 3

Claims (1)

[Claims] 1. A predetermined function that uniquely defines the correspondence between a parameter and a function value, and a predetermined function that uniquely defines a correspondence between the complement of the parameter and the same function value as the function value. Storage means for storing only one of the function values and outputting the function value corresponding to the parameter transmitted from the outside; and external switching of either the input logic variable or the complement of the logic variable. A digital function generator comprising: switching means for outputting parameters as parameters to the storage means in accordance with commands.